Peptide Critic

Peptide Critic
Available inEnglish
HeadquartersIncline Village, Nevada, U.S.
FounderJeff Colhoun
Websitepeptidecritic.com
RegistrationOptional

Peptide Critic is a website that aggregates reviews and laboratory documentation for synthetic peptides sold online under a "research use only" label. Its operators describe it as an independent comparison platform that does not manufacture or sell peptides. It has been used as a source in peer-reviewed preprint.

History

Wired (magazine) mentioned Jeff Colhoun as the founder. A 2026 survey on the Substack newsletter Peptides Weekly described Peptide Critic in contrast to Finnrick.

Peptide Critic was officially launched as a directory with live tracking, community reviews and links to scientific literature. In August and September 2026 the site published laboratory findings.

Laboratory reports

Brooklyn purchase (August 2026)

Peptide Critic stated that it bought four sealed vials of one brand from a Brooklyn smoke shop for about US$410 (two labeled 10 mg retatrutide, two labeled 500 mg NAD+) and sent them to Analytical Formulations, Inc. It reported that none matched the identity reference standard, so purity and quantity were "indeterminate" and stated the results do not establish the contents of other products.

Retatrutide storage test (September 2026)

A summary hosted by the peptide provider Helia Biochem describes six unopened, freeze-dried 10 mg retatrutide vials from one batch, stored from late May to 3 September 2026 in a refrigerator, a truck in Northern California and a sunlit windowsill, with two vials per condition assayed by TrustPointe Analytics. Mean measured content was 12.053 mg (refrigerator), 11.410 mg (truck) and 11.222 mg (windowsill); all HPLC purity results were 99.552–99.767%. The summary states that the design cannot establish degradation rates, lacking a time-zero assay, temperature logging or a room-temperature control.

Use in literature

A April 2026 preprint used Peptide Critic to obtain 271 parameters for four peptides (bremelanotide, semaglutide, tesamorelin and tirzepatide) for comparison with compounded and approved products.

See also

References

  1. ↑ "The Definitive Guide to the Peptide Critic Pen". Archaeology (magazine).
  2. 1 2 Mendias, Christopher L.; Awan, Tariq M. (24 April 2026). "Evaluation of Research Grade Peptides Marketed Directly to Consumers Reveals Extensive Variability in Purity and Measured Abundance". Preprints.org (Preprint). doi:10.20944/preprints202604.1748.v1.
  3. ↑ "Those Viral Bodega Peptides Aren't Actually Peptides". Wired (magazine). 15 September 2026.
  4. ↑ "The USA and International Peptide Vendor Directory". Peptides Weekly. 5 April 2026.
  5. ↑ "Editorial: Cost, Vial-Splitting". My Peptide Story.
  6. ↑ Hill, Tom (6 May 2026). "Retatrutide Supplier Guide: How to Evaluate Quality (2026)". GLP3 Planner.
  7. ↑ Mitchell, Alexander R. (1 January 2008). "Bruce Merrifield and solid-phase peptide synthesis: A historical assessment†". Peptide Science. 90 (3). John Wiley & Sons, Ltd: 175–184. doi:10.1002/bip.20925. ISSN 1097-0282. PMID 18213693.
  8. ↑ "What a Brooklyn bodega reveals about the craze for an experimental weight-loss drug - CBS News". CBS News. 2 July 2026.
  9. ↑ "Peptide Market Has Zero Pep Problem: We Found It in a Brooklyn Smoke Shop". Peptide Critic. August 13, 2026.
  10. 1 2 "Retatrutide Truck Heat Test: Summer Storage Results". Helia Biochem. 18 September 2026.
  11. ↑ Mollica, Adriano; Pinnen, Francesco; Azzurra, Stefanucci; Costante, Roberto (1 September 2013). "The Evolution of Peptide Synthesis: From Early Days to Small Molecular Machines". Bentham Science Publishers. 9 (3). Bentham Science Publishers: 184–202. doi:10.2174/157340720903140119151919. ISSN 1573-4072.